This paper reports on the contribution of a number of material coal properties and machine operating parameters to the wear of vertical spindle mill components, This assists in the evaluation of mills and coals for particular duties and enables prediction of the likely changes in maintenance regime if these variables are changed, Coal abrasiveness was found to be the most critical coal property with moisture next in importance. Feed rate was of importance with some interesting interactive affects, Roll grinding pressure was by far the most important machine variable with recirculation and air/coal ratio of lesser importance. Alloys used were characterized by Brinnell Hardness Number (BHN) and chromium alloy content.